Method of fabricating an electrode structure for use in an integrated circuit

ABSTRACT

An electrode structure includes a first layer of conductive material and a dielectric layer formed on a surface of the first layer. An opening is formed in the dielectric layer to expose a portion of the surface of the first layer. A binding layer is formed on the dielectric layer and on the exposed portion of the surface of the first layer and a second layer of conductive material is formed on the conductive binding layer. The binding layer can be an oxide and the second layer a conductive material that is diffusible into an oxide. The electrode structure can be annealed to cause conductive material from the second layer to be chemisorbed into the binding layer to improve adhesion between the first and second layers. A programmable cell can be formed by forming a doped glass layer in the electrode structure.

This application is a divisional of U.S. patent application Ser. No.09/988,984 filed Nov. 19, 2001, now U.S. Pat. No. 6,815,818 issued Nov.9, 2004, which is herein incorporated by reference in its entirety.

FIELD OF THE INVENTION

The present invention relates generally to semiconductor chips andintegrated circuits, and more particularly to an electrode structure foruse in integrated circuits, such as electronic systems, memory systemsand the like.

BACKGROUND OF THE INVENTION

In fabricating integrated circuits, semiconductor chips and the like,chemical/mechanical planarization can be used as an intermediateoperation to planarize a structure to provide a uniform, level surfacefor subsequent processing operations in the manufacturing of asemiconductor chip or integrated circuit. For example, electrodes orelectrical contacts between different layers of conductive materials ina semiconductor chip can be formed by depositing a first layer ofconductive material, typically a metal, although a semiconductormaterial could be used as well, and then depositing a thin dielectriclayer over the first conductive layer. The dielectric layer is thenpatterned to form at least one opening in the dielectric layer to exposea portion of the surface of the first conductive layer. The opening canhave a small aspect ratio of depth to width. For instance, the openingcan be about half a micron wide but only about 500 angstroms deep thuspresenting a aspect ratio of about 0.1. A second layer of a differentconductive material is then deposited on the dielectric layer and in theopening on the first conductive layer to make electrical contact throughthe opening with the first conductive layer. The second conductive layeris then removed form the dielectric layer or planarized to expose thedielectric layer and to form an isolated electrode or damascene contactstructure in the opening before subsequent fabrication operations. Inremoving the second conductive layer by chemical/mechanical processingor planarization (CMP), the forces created by the CMP process can have atendency to force the conductive material of the second layer out of theopening thereby destroying the contact.

Accordingly, for the reason stated above, and for other reasons thatwill become apparent upon reading and understanding the presentspecification, there is a need for an electrode structure and method offabrication that provides substantially improved adhesion between afirst layer of conductive material and second layer of a differentconductive material, particularly during a CMP operation, and that doesnot adversely effect the conductivity between the two layers or createan electrical barrier. There is also a need for a method of fabricatingan electrode structure that does not effect or damage other componentsthat may already have been formed on the same wafer or substrate andthat does not adversely effect the manufacturing process by requiring asignificant number of additional process operations.

SUMMARY OF THE INVENTION

The above mentioned problems with electrode structures are addressed bythe present invention and will be understood by reading and studying thefollowing specification. Electrode structures, memory cells and systemsare provided by the present invention that exhibit good adhesion betweendifferent conductive layers during manufacturing operations such as CMPwithout the conductivity between the layers being adversely effected.Methods of fabricating are also provided by the present invention thatdo not adversely effect other components that may have already beenformed on a semiconductor die.

In accordance with the present invention, an electrode structureincludes a first layer of conductive material and a dielectric layerformed on a surface of the first layer. An opening is formed in thedielectric layer to expose a portion of the surface of the first layer.A binding layer is formed on the dielectric layer and on the exposedportion of the surface of the first layer and a second layer ofconductive material is formed on the conductive binding layer.

In accordance with an embodiment of the present invention, a memorycell, includes a first layer of conductive material and a dielectriclayer formed on a surface of the first layer. An opening is formed inthe dielectric layer to expose a portion of the surface of the firstlayer. A binding layer is formed on the dielectric layer and on theexposed portion of the surface of the first layer and a second layer ofconductive material is formed on the binding layer. A layer of dopedchalcogenide material is formed on the second layer of conductivematerial and a third layer of conductive material is formed on the layerof doped chalcogenide material.

In accordance with another embodiment of the present invention, a methodof making an electrode, comprises: forming a first layer of conductivematerial; forming a dielectric layer on a surface of the first layer;forming an opening in the dielectric layer to expose a portion of thesurface of the first layer; forming a binding layer on the dielectriclayer and on the exposed portion of the surface of the first layer; andforming a second layer of conductive material on the binding layer. Theelectrode structure can be annealed at a selected temperature for apredetermined time period to cause conductive material from the secondlayer to be diffused into the binding layer to improve adhesion andconductivity between the first and second conductive layers.

In accordance with another embodiment of the present invention, a methodof making a memory cell, comprises: forming a first layer of conductivematerial; forming a dielectric layer on a surface of the first layer;forming an opening in the dielectric layer to expose a portion of thesurface of the first layer; forming a binding layer on the dielectriclayer and on the exposed portion of the surface of the first layer;forming a second layer of conductive material on the binding layer;forming a layer of doped chalcogenide material on the second layer ofconductive material; and forming a third layer of conductive material onthe layer of doped chalcogenide material. The layer of chalcogenidematerial can be doped by annealing the memory cell to cause conductivematerial from the third layer to be chemisorbed into the chalcogenidelayer.

These and other embodiments, aspects, advantages and features of thepresent invention will be set forth in part in the description whichfollows, and in part will become apparent to those skilled in the art byreference to the following description of the invention and referenceddrawings or by practice of the invention. The aspects, advantages, andfeatures of the invention are realized and attained by means of theinstrumentalities, procedures, and combinations particularly pointed outin the appended claims.

BRIEF DESCRIPTION OF THE DRAWINGS

In the drawings, like numerals describe substantially similar componentsthroughout the several views. Like numerals having different lettersuffixes or primed (X′) represent different occurrences of substantiallysimilar components.

FIGS. 1A–1C illustrate the operations in forming an electrode for use inan integrated circuit in accordance with the present invention.

FIGS. 2A–D illustrate the operations in forming a programmable memorycell in accordance with an embodiment of the present invention.

FIGS. 3A–3E illustrate the operations in forming a programmable memorycell in accordance with another embodiment of the present invention.

FIG. 4 is a schematic diagram of a memory system incorporating aprogrammable memory cell in accordance with the present invention.

FIG. 5 is a top view of a wafer or substrate containing semiconductordies in accordance with an embodiment of the present invention.

FIG. 6 is a block schematic diagram of a circuit module in accordancewith an embodiment of the present invention.

FIG. 7 is a block schematic diagram of a memory module in accordancewith an embodiment of the present invention.

FIG. 8 is a block schematic diagram of an electronic system inaccordance with another embodiment the present invention.

FIG. 9 is a block schematic diagram of a memory system in accordancewith an embodiment of the present invention.

FIG. 10 is a block schematic diagram of a computer system in accordancewith an embodiment of the present invention.

DESCRIPTION OF THE EMBODIMENTS

In the following detailed description of the preferred embodiments,reference is made to the accompanying drawings which form a part hereof,and in which is shown by way of illustration specific embodiments inwhich the invention may be practiced. These embodiments are described insufficient detail to enable those skilled in the art to practice theinvention, and it is to be understood that other embodiments can beutilized and that process or mechanical changes may be made withoutdeparting from the scope of the present invention. The terms wafer andsubstrate used in the following description include any basesemiconductor structure. Both are to be understood as includingsilicon-on-sapphire (SOS) technology, silicon-on-insulator (SOI)technology, thin film transistor (TFT) technology, doped and undopedsemiconductors, epitaxial layers of a silicon supported by a basesemiconductor, as well as other semiconductor support structures wellknown to one skilled in the art. Furthermore, when reference is made toa wafer or substrate in the following description, previous processoperations may have been utilized to form regions/junctions in the basesemiconductor structure. The following detailed description is,therefore, not to be taken in a limiting sense, and the scope of thepresent invention is defined only by the appended claims.

The transistors described herein include transistors frombipolar-junction technology (BJT), field effect technology (FET), orcomplimentary metal-oxide-semiconductor (CMOS) technology. Ametal-oxide-semiconductor (MOS) transistor includes a gate, a first node(drain) and a second node (source). Since a MOS transistor is typicallya symmetrical device, the true designation of “source” and “drain” isonly possible once voltage is impressed on the terminals. Thedesignations of source and drain herein should be interpreted,therefore, in the broadest sense. It should also be noted that aP-channel MOS transistor could alternatively be used for an N-channelMOS transistor and vice versa with the polarity of the associated gatevoltages merely being reversed. For example, applying a negative gatevoltage in the situation of a P-channel MOS transistor to activate thetransistor and reversing the polarity to apply a positive gate voltageto activate an N-channel transistor if an N-channel MOS transistor issubstituted for a P-channel transistor.

FIGS. 1A–1C illustrate the operations in forming an electrode structure100 in accordance with the present invention. In FIG. 1A, a first layer102 of conductive material is deposited or formed. The first layer 102of conductive material can be tungsten, nickel or a semiconductormaterial. A dielectric layer 104 is formed on the first conductive layer102. The dielectric layer 104 can be a nitride, such as silicon nitrideor a similar dielectric material. The dielectric layer 104 is patternedby standard photolithographic techniques or the like to form at leastone opening 106 through the dielectric layer 104 to expose a portion ofa surface 108 of the first conductive layer 102. The opening 106 canhave a width “W” or a diameter that is significantly larger than a depth“D” to provide a small aspect ratio; however, the invention is notlimited to such aspect ratios. A layer 110 of oxide is formed on thedielectric layer 104 and on the surface 108 of the first conductivelayer 102. The oxide layer 110 can be a silicon oxide deposited by thethermal reaction of a precursor, such as tetraethyl orthosilicate (TEOS)or the like. The oxide layer 110 can have a thickness between about 50angstroms and about 200 angstroms. A second layer 112 of conductivematerial is formed on the oxide layer 110. The second layer 112 ofconductive material can be silver, nickel or another metal or conductivematerial that can diffuse into the oxide layer 110 and bond to the oxidelayer 110.

In FIG. 1B, the electrode structure 100B is annealed in an inert ambientenvironment at a selected temperature for a predetermined time period.The inert ambient environment can be nitrogen, argon or some other gasthat is non-reactive to the materials forming the electrode structure100. For an oxide layer 110 of TEOS and a second conductive layer 112 ofsilver, annealing at about 350° Celsius for about ten minutes providesthe proper amount of diffusion or chemisorption of silver molecules intothe TEOS to make the oxide layer 110 at least semiconductive so as tonot create an electrical barrier between the first and second conductivelayers 102 and 112. The oxide layer 110 is therefore converted into aconductive or at least semiconductive binding layer 110′ by theannealing operation. The electrode structure 100B can be annealed attemperatures as low as about 130° Celsius or room temperature; however,the time period to achieve the proper level of chemisorption will bemuch longer thereby increasing the amount of time overall for themanufacturing process. According to the present invention, the annealingtemperature and time period can be adjusted to control the rate andamount of diffusion or chemisorption of molecules of the conductivematerial or metal from the second layer 112 into the oxide layer 110.The annealing temperature and time period are also selected withconsideration of other components and subsequent processing steps so asto not adversely effect or damage other components that have alreadybeen formed on a wafer or semiconductor die or that would result inadditional processing operations that would increase the cost and timeto manufacture a semiconductor chip.

In FIG. 1C, the electrode structure can be planarized to form anisolated electrode structure or damascene layer 114 and to form a levelor more uniform surface 116 for subsequent processing operations. Theplanarization of the electrode structure 100C can be accomplished by achemical/mechanical planarization (CMP) process or the like. Inaccordance with the present invention, the binding layer 110′ isselected to provide sufficient adhesion between the first and secondconductive layers 102 and 112 to prevent the forces created by the CMPprocess from forcing or warping out the damascene layer 114.

In FIGS. 2A–2D, the process operations are shown to form a programmablememory or metallization cell structure 200 in accordance with anembodiment of the present invention that can be used in a memory system,such as a programmable cell random access memory (PCRAM) device or thelike. In FIG. 2A, a first conductive layer 202 is formed. The firstconductive layer 202 can be a metal, such as tungsten, nickel or thelike, or the first conductive layer 202 can be a semiconductor orpolysilicon material. A layer 204 of dielectric material is formed onthe first conductive layer 202. The dielectric layer 204 can be anitride, for example silicon nitride or a similar dielectric. Thedielectric layer 204 is selectively patterned by standardphotolithographic techniques or similar material removal techniques toform at least one opening 206 in the dielectric layer 204 and to exposea portion of a surface 208 of the first conductive layer 202. Theopening 206 can have a depth dimension “D” that is much smaller than awidth dimension “W” to define a small aspect ratio of depth to width.The invention, however, is not so limited. A layer 210 of oxide isformed on the dielectric layer 204 and on the exposed surface portion208 of the first conductive layer 202. The oxide layer 210 can be asilicon dioxide. The oxide layer 210 can have a thickness between about50 angstroms and about 100 angstroms. A second layer 212 of conductivematerial is formed on the oxide layer 210 and in the opening 206. Thesecond conductive layer 212 can be a metal, such as silver, nickel,polysilicon or other conductive material that is diffusible into anoxide and exhibits good adhesion to an oxide. The second conductivelayer can have a thickness between about 50 angstroms and about 500angstroms depending upon other parameters or features of the memory cellstructure 200.

In FIG. 2B, the memory cell structure 200B is annealed at a selectedtemperature for a predetermined time period in an inert ambientenvironment, such as nitrogen, argon or some other gas that isnon-reactive to the materials forming the cell structure 200. As anexample, for an oxide layer 210 of TEOS and a second conductive layer212 of silver, annealing at about 350° Celsius for about 10 minutesprovides the appropriate level of diffusion or chemisorption of silvermolecules into the TEOS oxide layer 210 to make the oxide layer 210 atleast semiconductive so as to not create an electrical barrier betweenthe first and second conductive layers 202 and 212. The oxide layer 210becomes a conductive or semiconductive binding layer 210′ as a result ofthe annealing operation and provides stronger adhesion between the firstand second conductive layers 202 and 212 as a result of the annealingprocess for stability of the structure 200 during subsequentmanufacturing operations such as CMP. As one of ordinary skill in theart will understand by reading and comprehending this disclosure, theannealing temperature and time can be adjusted to control the rate andamount of chemisorption of silver or conductive material from the secondconductive layer 212 into the oxide layer 210 and to also control theimpact on previously formed structures or devices on the wafer orsemiconductor chip. Because of the diffusion of conductive materialduring the annealing process, the resulting conductive binding layer210′ defines an electrical contact or interface between the first andsecond conductive layers 202 and 212.

In FIG. 2C, a layer 214 of chalcogenide glass material is formed on theon the second conductive layer 212 and in the opening 206. The layer 214of chalcogenide glass material can be germanium selenide(Ge_(X)Se_(1−X), where X is the concentration of germanium and 1-X isthe concentration of selenide). In one embodiment according to theteachings of the present invention, the concentration ratio of germaniumto selenide can be between about 15/85 and about 40/60. A third layer216 of conductive material is formed on the layer 214. The thirdconductive layer 216 can be a metal such as silver, nickel or anothermetal that is diffusible into a chalcogenide material. The layer 214 isdoped by annealing the memory cell structure 200C to cause metal orconductive material from the third layer 216 to diffuse into thechalcogenide layer 214 to a selected concentration. The annealingprocess can be ultra violet annealing or a similar annealing process.The annealing process also improves adhesion between the thirdconductive layer 216 and the chalcogenide layer 214 resulting in ahighly adhesive cell structure 200C that can withstand the forces orpressures applied by subsequent manufacturing operations such as CMP.

In FIG. 2D, the cell structure 200D is planarized to form an isolatedcell structure 200D or third layer contact or damascene layer 216′ andto provide a level or more uniform surface 218 for subsequent processingoperations. The cell structure 200D can be planarized by CMP or thelike. A fourth layer 220 of conductive material can be formed on theplanarized surface 218 and in electrical contact with the third layercontact 216′.

The conductive material or metallization of the second layer 212 formedon the sidewalls 222 of the opening 206 can be minimized by thedeposition process and is substantially diffused into the oxide layer210 on the sidewalls 222 during the annealing process. In this manner,no isolation or dielectric is required between any residualmetallization on the sidewalls 222 and the fourth layer of conductivematerial 220 that would necessitate additional process steps after theCMP operation and before the fourth layer 220 is formed.

FIGS. 3A–3E illustrate the operations in forming a programmable memorycell 300 in accordance with another embodiment of the present inventionthat forms a reentrant profile to prevent conductive material fromforming on the sidewalls of the opening in the dielectric layer. In FIG.3A, a first conductive layer 302 is formed. The first conductive layer302 can be a metal such as tungsten, nickel, or the like, or asemiconductor material or polysilicon. A first dielectric layer 304having one etch rate is formed on the first conductive layer 302 and asecond dielectric layer 306 having a second etch rate is formed on thefirst dielectric layer 304. In accordance with the present invention,the etch rate of the first dielectric layer 304 is faster than the etchrate of the second dielectric layer 306. Accordingly, in FIG. 2B, whenthe first and second dielectric layers 304 and 306 are selectivelypatterned to form an opening 308, the opening has a reentrant profilewith sidewalls 310 that angle back as the opening 308 extends down toexpose the first conductive layer 302. A layer 312 of oxide is formed onthe second dielectric layer 306 and on an exposed surface portion 314 ofthe first conductive layer 302 in the opening 308. The oxide layer 312can be a silicon oxide. A second layer 316 of conductive material isformed on the oxide layer 312. The second conductive layer 316 can besilver, nickel or another conductive material or metal that isdiffusible into an oxide. Because of the reentrant profile of theopening 308, the second conductive layer 316 and oxide layer 312 cannotform on the sidewalls 310 of the opening 308.

In FIG. 3C, the cell structure 300C is annealed at a selectedtemperature for a predetermined time period to cause metallization orconductive material from the second conductive layer 316 to diffuse intothe oxide layer 312 to form a conductive binding layer 312′. Theconductive binding layer 312′ provides electrical contact and adhesionbetween the first and second conductive layers 302 and 316 duringsubsequent processing operations such as CMP. As previously discussed,the annealing temperature and time can be adjusted to control the amountof chemisorption of metal molecules into the oxide layer 312 and tocontrol the impact on other components or devices already formed on thewafer or semiconductor chip.

In FIG. 3D, a layer 318 of chalcogenide glass material is formed on theon the second conductive layer 316 and in the opening 308. The layer 318of chalcogenide glass material can be germanium selenide(Ge_(X)Se_(1−X), where X is the concentration of germanium and 1-X isthe concentration of selenide). As previously discussed, according tothe teachings of the present invention, the concentration ratio ofgermanium to selenide can be between about 15/85 and about 40/60. Athird layer 320 of conductive material is formed on the layer 318. Thethird conductive layer 318 can be a metal such as silver, nickel oranother metal that is diffusible into a chalcogenide material. The layer318 is doped by annealing the memory cell structure 300D to cause metalor conductive material from the third layer 320 to diffuse into thechalcogenide layer 318 to bond the two layers together and providebetter adhesion.

In FIG. 3E, the cell structure 300E is planarized to form an isolatedcell structure 300E including an isolated third layer contact orelectrode 320′. The planarization also provides a level, more uniformsurface 322 for subsequent processing operations. The cell structure300E can be planarized by CMP or the like. A fourth layer 324 ofconductive material can be formed on the planarized surface 322 and inelectrical contact with the third layer electrode or contact 320′.

In operation, the programmable memory cell 200 or 300 or programmablemetallization cell can be programmed by applying a potential or voltageacross the first layer or electrode 302 and the third layer electrode320′ that has a sufficient voltage level to cause a dendrite 326 orconductive filament to be formed between the electrode 320′ and thesecond conductive layer 316 which is electrically connected to the firstlayer electrode 302 by the conductive binding layer 312′. Because thechalcogenide layer 322 is doped with a metal or conductive material suchas silver, the voltage causes the dendrite 326 (226 in FIG. 2D) to beformed to short circuit the two electrodes 320′ and 302. The resistanceacross a cell 300 that has been biased by applying sufficient voltage toform the dendrite 326 is about 10,000 ohms. The resistance of a cell 300that has not been biased and is in an open condition is about 10megohms. Accordingly, a programmed cell 300 to which a voltage has beenapplied to form the dendrite 326 can represent a logic 1 and anunprogrammed or open cell 300 can represent a logic 0. To erase aprogrammed cell 300, a reverse polarity voltage can be applied to theelectrodes 320′ and 302 of the cell 300 to cause sufficient current toflow through the cell 300 to return the cell 300 to a high resistancestate by destruction of the dendrite 326 or conductive element.

FIG. 4 is a schematic diagram of a memory device or system 400 inaccordance with the present invention. The memory system 400 includes aplurality of memory elements 402 that can be arranged in rows andcolumns. Each memory element 402 can include a transistor 404. Eachtransistor 404 includes a gate electrode 406 coupled to an address line408 for controlling the operation of the memory element 402, and eachtransistor 404 includes a first source/drain electrode 410 coupled to adata line 412 and a second source/drain electrode 414 coupled to aprogrammable memory cell 416 according to the teachings of the presentinvention, e.g. similar to the memory cells 200D (FIG. 2D) and 300E(FIG. 3E).

With reference to FIG. 5, a semiconductor die 510 can be produced from asilicon wafer 500 that can contain a memory system similar to system 400or an electronic system including the novel electrode structure 100C(FIG. 1E) or memory cells 200D (FIG. 2D) or 300E (FIG. 3E) in accordancewith the present invention. A die 510 is an individual pattern,typically rectangular, on a substrate that contains circuitry to performa specific function. A semiconductor wafer 500 will typically contain arepeated pattern of such dies 510 containing the same functionality. Die510 can further contain additional circuitry to extend to such complexdevices as a monolithic processor with multiple functionality. Die 510is typically packaged in a protective casing (not shown) with leadsextending therefrom (not shown) providing access to the circuitry of thedie 510 for unilateral or bilateral communication and control.

As shown in FIG. 6, two or more dies 510, including at least oneelectronic system or memory system 400 that incorporates the novelelectrode structure 100C or memory cells 200D or 300E in accordance withthe present invention, can be combined, with or without a protectivecasing, into a circuit module 600 to enhance or extend the functionalityof an individual die 510. Circuit module 600 can be a combination ofdies 510 representing a variety of functions, or a combination of dies510 containing the same functionality. Some examples of a circuit module600 include memory modules, device drivers, power modules, communicationmodems, processor modules and application-specific modules and caninclude multi-layer, multi-chip modules. Circuit module 600 can be asub-component of a variety of electronic systems, such as a clock, atelevision, a cell phone, a personal computer, an automobile, anindustrial control system, an aircraft and others. Circuit module 600will have a variety of leads 610 extending therefrom providingunilateral or bilateral communication and control.

FIG. 7 shows one embodiment of a circuit module as a memory module 700containing circuitry for the memory system 400 including the electrodestructure 100C or memory cell structures 200D or 300E of the presentinvention. Memory module 700 generally depicts a Single In-line MemoryModule (SIMM) or Dual In-line Memory Module (DIMM). A SIMM or DIMM cangenerally be a printed circuit board (PCB) or other support containing aseries of memory devices. While a SIMM will have a single in-line set ofcontacts or leads, a DIMM will have a set of leads on each side of thesupport with each set representing separate I/O signals. Memory module700 contains multiple memory devices 710 contained on support 715, thenumber depending upon the desired bus width and the desire for parity.Memory module 700 can contain memory devices 710 on both sides ofsupport 715. Memory module 700 accepts a command signal from an externalcontroller (not shown) on a command link 720 and provides for data inputand data output on data links 730. The command link 720 and data links730 are connected to leads 740 extending from the support 715. Leads 740are shown for conceptual purposes and are not limited to the positionsshown in FIG. 7.

FIG. 8 shows an electronic system 800 containing one or more circuitmodules 600 as described above containing the novel memory system 400and electrode structure 100C or memory cells 200D or 300E of the presentinvention. Electronic system 800 generally contains a user interface810. User interface 810 provides a user of the electronic system 800with some form of control or observation of the results of theelectronic system 800. Some examples of user interface 810 include thekeyboard, pointing device, monitor and printer of a personal computer;the tuning dial, display and speakers of a radio; the ignition switchand gas pedal of an automobile; and the card reader, keypad, display andcurrency dispenser of an automated teller machine. User interface 810can further describe access ports provided to electronic system 800.Access ports are used to connect an electronic system to the moretangible user interface components previously exemplified. One or moreof the circuit modules 600 can be a processor providing some form ofmanipulation, control or direction of inputs from or outputs to userinterface 810, or of other information either preprogrammed into, orotherwise provided to, electronic system 800. As will be apparent fromthe lists of examples previously given, electronic system 800 will oftencontain certain mechanical components (not shown) in addition to thecircuit modules 600 and user interface 810. It will be appreciated thatthe one or more circuit modules 600 in electronic system 800 can bereplaced by a single integrated circuit. Furthermore, electronic system800 can be a sub-component of a larger electronic system.

FIG. 9 shows one embodiment of an electronic system as memory system900. Memory system 900 contains one or more memory modules 700 asdescribed above including the memory system 400 and electrode structure100C or memory cells 200D and 300E in accordance with the presentinvention and a memory controller 910. Memory controller 910 providesand controls a bidirectional interface between memory system 900 and anexternal system bus 920. Memory system 900 accepts a command signal fromthe external bus 920 and relays it to the one or more memory modules 700on a command link 930. Memory system 900 provides for data input anddata output between the one or more memory modules 700 and externalsystem bus 920 on data links 940.

FIG. 10 shows a further embodiment of an electronic system as a computersystem 1000. Computer system 1000 contains a processor 1010 and a memorysystem 900 housed in a computer unit 1005. Computer system 1000 is butone example of an electronic system containing another electronicsystem, i.e. memory system 900, as a sub-component, including the memorysystem 400 and electrode structure 100C or memory cells 200D and 300E inaccordance with the present invention. Computer system 1000 optionallycontains user interface components. Depicted in FIG. 10 are a keyboard1020, a pointing device 1030, a monitor 1040, a printer 1050 and a bulkstorage device 1060. It will be appreciated that other components areoften associated with computer system 1000 such as modems, device drivercards, additional storage devices, etc. It will further be appreciatedthat the processor 1010 and memory system 900 of computer system 1000can be incorporated on a single integrated circuit. Such single packageprocessing units reduce the communication time between the processor1010 and the memory system 900.

CONCLUSION

The present invention thus provides an electrode structure and memorycell structure and method of fabrication that provides substantiallyimproved adhesion between two layers of conductive material duringsubsequent processing operations, such as a CMP operation. The electrodestructure and memory cell structure of the present invention also canprovide a conductive interface between the two conductive layers that isnot an electrical barrier and can provide a doped glass layer that canbe programmed to store data. The present invention also provides amethod of fabricating an electrode structure or memory cell structurethat does not adversely effect subsequent processing operations orrequire additional processing operations and the process can becontrolled to avoid damage to other components that may already havebeen formed on the same wafer or substrate.

Although specific embodiments have been illustrated and describedherein, it will be appreciated by those of ordinary skill in the artthat any arrangement which is calculated to achieve the same purpose maybe substituted for the specific embodiments shown. This application isintended to cover any adaptations or variations of the presentinvention. Therefore, it is intended that this invention be limited onlyby the claims and the equivalents thereof.

1. A method of making a memory cell, comprising: forming a first layerof conductive material; forming a dielectric layer on a surface of thefirst layer; forming an opening in the dielectric layer to expose aportion of the surface of the first layer; forming an oxide bindinglayer over the dielectric layer and over the exposed portion of thesurface of the first layer, wherein the oxide binding layer can be madeconductive or at least semi-conductive; forming a second layer ofconductive material on the oxide binding layer; forming a layer of dopedchalcogenide material on the second layer of conductive material; andforming a third layer of conductive material on the layer of dopedchalcogenide material.
 2. A method of making a memory cell, comprising:forming a first layer of conductive material; forming a dielectric layeron a surface of the first layer; forming an opening in the dielectriclayer to expose a portion of the surface of the first layer; forming aconductive binding layer including silicon dioxide over the dielectriclayer and over the exposed portion of the surface of the first layer;forming a second layer of conductive material on the conductive bindinglayer; forming a layer of germanium selenide material on the secondlayer of conductive material; forming a third layer of conductivematerial on the layer of germanium selenide; and annealing the memorycell to cause conductive material from the third layer to diffuse intothe layer of germanium selenide.
 3. The method of claim 2, wherein theconcentration of germanium to selenide in the germanium selenide layeris between about 15/85 and about 40/60.
 4. A method of making a memorycell, comprising: forming a first layer of metallization; forming adielectric layer on a surface of the first layer; forming an opening inthe dielectric layer to expose a portion of the surface of the firstlayer; forming a binding layer including silicon dioxide over thedielectric layer and over the exposed portion of the surface of thefirst layer, wherein the binding layer including silicon dioxide can bemade conductive or at least semi-conductive: forming a second layer ofmetallization on the binding layer; diffusing metallization from thesecond layer into the binding layer; forming a layer of chalcogenidematerial on the second layer of metallization; forming a third layer ofmetallization on the layer of chalcogenide material; and annealing thememory cell to cause metallization from the third layer to diffuse intothe layer of chalcogenide material.
 5. A method of making a memory cell,comprising: forming a first layer of one of tungsten, nickel orpolysilicon; forming a dielectric layer on a surface of the first layer;forming an opening in the dielectric layer to expose a portion of thesurface of the first layer; forming a conductive binding layer includinga silicon dioxide on the dielectric layer and on the exposed portion ofthe surface of the first layer, wherein the conductive binding layer isformed from annealed insulating materials; forming a second layer of oneof silver or nickel on the conductive binding layer; diffusing silver ornickel into the binding layer from the second layer by annealing at aselected temperature for a predetermined period of time; forming a layerof germanium selenide material on the second layer of silver or nickel;forming a third layer including silver or nickel on the layer ofgermanium selenide; and annealing the memory cell to cause apredetermined level of chemisorption of silver or nickel from the thirdlayer to diffuse into the layer of germanium selenide material.
 6. Amethod of making a memory cell, comprising: forming a first layer ofconductive material; forming a first dielectric layer on a surface ofthe first layer; forming a second dielectric layer on the firstdielectric layer; forming an opening in the first and second dielectriclayers to expose a portion of the surface of the first layer, whereinthe opening includes a reentrant profile in response to a difference inan etch rate between the first and second dielectric layers; forming anoxide binding layer on the second dielectric layer and on the exposedportion of the surface of the first layer, wherein the oxide bindinglayer can be made conductive or at least semi-conductive; forming asecond layer of conductive material on the binding layer; forming alayer of chalcogenide material on the second layer of conductivematerial; forming a third layer of conductive material on the layer ofchalcogenide material; and annealing the memory cell to cause conductivematerial from the third layer to be chemisorbed by the layer ofchalcogenide material.
 7. A method of making a memory system,comprising: forming an array of memory elements; and forming a memorycell associated with each memory element, wherein forming each memorycell includes: forming a first layer of conductive material; forming adielectric layer on a surface of the first layer; forming an opening inthe dielectric layer to expose a portion of the surface of the firstlayer; forming an oxide binding layer over the dielectric layer and overthe exposed portion of the surface of the first layer, wherein the oxidebinding layer can be made conductive or at least semi-conductive;forming a second layer of conductive material on the oxide bindinglayer; forming a layer of doped chalcogenide material on the secondlayer of conductive material; and forming a third layer of conductivematerial on the layer of doped chalcogenide material.
 8. A method ofmaking a memory system, comprising: forming an array of memory elements;and forming a memory cell associated with each memory element, whereinforming each memory cell includes: forming a first layer of conductivematerial; forming a dielectric layer on a surface of the first layer;forming an opening in the dielectric layer to expose a portion of thesurface of the first layer; forming an oxide binding layer over thedielectric layer and over the exposed portion of the surface of thefirst layer, wherein the oxide binding layer can be made conductive orat least semi-conductive; forming a second layer of conductive materialon the binding layer; forming a layer of germanium selenide material onthe second layer of conductive material; forming a third layer ofconductive material on the layer of germanium selenide material; andannealing the memory cell to cause conductive material from the thirdlayer to diffuse into the layer of germanium selenide.
 9. A method ofmaking a memory system, comprising: forming an array of memory elements;and forming a memory cell associated with each memory element, whereinforming each memory cell includes: forming a first layer of one oftungsten, nickel or polysilicon; forming a dielectric layer on a surfaceof the first layer; forming an opening in the dielectric layer to exposea portion of the surface of the first layer; forming a conductivebinding layer including a silicon dioxide over the dielectric layer andover the exposed portion of the surface of the first layer, wherein theconductive binding layer is formed from annealed insulating materials;forming a second layer of one of silver or nickel on the conductivebinding layer, diffusing silver or nickel into the binding layer fromthe second layer by annealing at a selected temperature for apredetermined period of time; forming a layer of germanium selenidematerial on the second layer of silver or nickel; forming a third layerincluding silver or nickel on the layer of germanium selenide; andannealing the memory cell to cause a predetermined level ofchemisorption of silver or nickel from the third layer to diffuse intothe layer of germanium selenide material.
 10. A method of making amemory system, comprising: forming an array of memory elements arrangedin rows and columns; forming a plurality of address lines each coupledto one of a row or a column of memory elements; and forming a pluralityof data lines each coupled to one of a row or a column of memoryelements, wherein forming each memory element includes: forming atransistor including a gate terminal coupled to one of the plurality ofaddress lines and a source/drain terminal coupled to one of theplurality of data lines; and forming a memory cell coupled to anothersource/drain terminal of the transistor, wherein forming the memory cellincludes: forming a first layer of conductive material; forming adielectric layer on a surface of the first layer; forming an opening inthe dielectric layer to expose a portion of the surface of the firstlayer; forming an oxide binding layer over the dielectric layer and overthe exposed portion of the surface of the first layer, wherein the oxidebinding layer can be made conductive or at least semi-conductive;forming a second layer of conductive material on the oxide bindinglayer; forming a layer of doped chalcogenide material on the secondlayer of conductive material; and forming a third layer of conductivematerial on the layer of doped chalcogenide material.
 11. A method ofmaking a memory system, comprising: forming an array of memory elementsarranged in rows and columns; forming a plurality of address lines eachcoupled to one of a row or a column of memory elements; and forming aplurality of data lines each coupled to one of a row or a column ofmemory elements, wherein forming each memory element includes: forming atransistor including a gate terminal coupled to one of the plurality ofaddress lines and a source/drain terminal coupled to one of theplurality of data lines; and forming a memory cell coupled to anothersource/drain terminal of the transistor, wherein forming the memory cellincludes: forming a first layer of one of tungsten, nickel orpolysilicon; forming a dielectric layer on a surface of the first layer;forming an opening in the dielectric layer to expose a portion of thesurface of the first layer; forming a binding layer including a silicondioxide over the dielectric layer and over the exposed portion of thesurface of the first layer, wherein the binding layer including thesilicon dioxide can be made conductive or at least semi-conductive;forming a second layer of one of silver or nickel on the conductivebinding layer; diffusing silver or nickel into the binding layer fromthe second layer by annealing at a selected temperature for apredetermined period of time; forming a layer of germanium selenidematerial on the second layer of silver or nickel; forming a third layerincluding silver or nickel on the layer of germanium selenide; andannealing the memory cell to cause a predetermined level ofchemisorption of silver or nickel from the third layer to diffuse intothe layer of germanium selenide material.
 12. A method of making anelectronic system, comprising: forming a processor; and forming a memorysystem coupled to the processor, wherein forming the memory systemincludes: forming an array of memory elements; and forming a memory cellassociated with each memory element, wherein forming each memory cellincludes: forming a first layer of conductive material; forming adielectric layer on a surface of the first layer; forming an opening inthe dielectric layer to expose a portion of the surface of the firstlayer; forming an oxide binding layer over the dielectric layer and overthe exposed portion of the surface of the first layer, wherein the oxidebinding layer can be made conductive or at least semi-conductive;forming a second layer of conductive material on the binding layer;forming a layer of doped chalcogenide material on the second layer ofconductive material; and forming a third layer of conductive material onthe layer of doped chalcogenide material.
 13. A method of making anelectronic system, comprising: forming a processor; and forming a memorysystem coupled to the processor, wherein forming the memory systemincludes: forming an array of memory elements; and forming a memory cellassociated with each memory element, wherein forming each memory cellincludes: forming a first layer of conductive material; forming adielectric layer on a surface of the first layer; forming an opening inthe dielectric layer to expose a portion of the surface of the firstlayer; forming an oxide binding layer over the dielectric layer and overthe exposed portion of the surface of the first layer, wherein the oxidebinding layer can be made conductive or at least semi-conductive;forming a second layer of conductive material on the oxide bindinglayer; forming a layer of germanium selenide material on the secondlayer of conductive material; forming a third layer of conductivematerial on the layer of conductive material; and annealing the memorycell to cause conductive material from the third layer to diffuse intothe layer of germanium selenide.
 14. A method of making an electronicsystem, comprising: forming a processor; and forming a memory systemcoupled to the processor and including a plurality of memory cells,wherein forming the memory system: forming an array of memory elementsarranged in rows and columns; forming a plurality of address lines eachcoupled to one of a row or a column of memory elements; and forming aplurality of data lines each coupled to one of a row or a column ofmemory elements, wherein forming each memory element includes: forming atransistor including a gate terminal coupled to one of the plurality ofaddress lines and a source/drain terminal coupled to one of theplurality of data lines; and forming a memory cell coupled to anothersource/drain terminal of the transistor, wherein forming the memory cellincludes: forming a first layer of conductive material; forming adielectric layer on a surface of the first layer; forming an opening inthe dielectric layer to expose a portion of the surface of the firstlayer; forming an oxide binding layer over the dielectric layer and overthe exposed portion of the surface of the first layer, wherein the oxidebinding layer can be made conductive or at least semi-conductive;forming a second layer of conductive material on the binding layer;forming a layer of doped chalcogenide material on the second layer ofconductive material; and forming a third layer of conductive material onthe layer of doped chalcogenide material.
 15. A method of making anelectronic system, comprising: forming a processor; and forming a memorysystem coupled to the processor and including a plurality of memorycells, wherein forming the memory system: forming an array of memoryelements arranged in rows and columns; forming a plurality of addresslines each coupled to one of a row or a column of memory elements; andforming a plurality of data lines each coupled to one of a row or acolumn of memory elements, wherein forming each memory element includes:forming a transistor including a gate terminal coupled to one of theplurality of address lines and a source/drain terminal coupled to one ofthe plurality of data lines; and forming a memory cell coupled toanother source/drain terminal of the transistor, wherein forming thememory cell includes: forming a first layer of conductive material;forming a dielectric layer on a surface of the first layer; forming anopening in the dielectric layer to expose a portion of the surface ofthe first layer; forming an oxide binding layer on the dielectric layerand on the exposed portion of the surface of the first layer, whereinthe oxide binding layer can be made conductive or at leastsemi-conductive; forming a second layer of conductive material on thebinding layer; forming a layer of doped chalcogenide material on thesecond layer of conductive material; and forming a third layer ofconductive material on the doped layer of chalcogenide material.
 16. Amethod of making a memory cell, comprising: forming a first layer ofconductive material; forming a dielectric layer on a surface of thefirst layer; forming an opening in said dielectric layer to expose aportion of a surface of said first layer; forming an oxide binding layerover said dielectric layer and over said exposed portion of a surface ofsaid first layer, wherein the oxide binding layer can be made conductiveor at least semi-conductive; forming a second layer of conductivematerial on said binding layer; forming a layer of variable resistancematerial over said second layer of conductive material, said variableresistance material being able to change resistance under the influenceof an applied voltage; and forming a third layer of conductive materialover said layer of variable resistance material.
 17. The method ofmaking a memory cell of claim 16, wherein said second layer ofconductive material is a metal layer and said oxide binding layercomprises a metal from said second layer diffused into said oxide layer.18. A method of making a memory system, comprising: forming an array ofmemory elements; and forming a memory cell associated with each memoryelement, wherein forming each memory cell includes: forming a firstlayer of conductive material; forming a dielectric layer on a surface ofthe first layer; forming an opening in the dielectric layer to expose aportion of the surface of the first layer; forming an oxide bindinglayer over the dielectric layer and over the exposed portion of asurface of said first layer, wherein the oxide binding layer can be madeconductive or at least semi-conductive; forming a second layer ofconductive material on the oxide binding layer; forming a layer ofvariable resistance material over said second layer of conductivematerial, said variable resistance material being able to changeresistance under the influence of an applied voltage; and forming athird layer of conductive material over said layer of variableresistance material.
 19. The method of making a memory system of claim18, wherein said second layer of conductive material is a metal layerand said oxide binding layer comprises a metal from said second layerdiffused into said oxide layer.
 20. A method of making an electronicsystem, comprising: forming a processor; and forming a memory systemcoupled to the processor, wherein forming the memory system includes:forming an array of memory elements; and forming a memory cellassociated with each memory element, wherein forming each memory cellincludes: forming a first layer of conductive material; forming adielectric layer on a surface of the first layer; forming an openingincluding a reentrant profile in the dielectric layer to expose aportion of a surface of said first layer; forming a conductive bindinglayer including silicon dioxide on the dielectric layer and on theexposed portion of the surface of the first layer; forming a secondlayer of conductive material on the conductive binding layer; forming alayer of variable resistance material over said second layer ofconductive material, said variable resistance material being able tochange resistance under the influence of an applied voltage; and forminga third layer of conductive material on said layer of variableresistance material.
 21. The method of making an electronic system ofclaim 20, wherein said second layer of conductive material is a metallayer and said binding layer comprises an oxide layer and metal fromsaid second layer diffused into said oxide layer.
 22. A method of makinga memory cell, comprising: forming a first layer of conductive material;forming an oxide binding layer on a surface of said first layer, whereinsaid oxide binding layer can be made conductive or at leastsemi-conductive; forming a second layer of conductive material on saidbinding layer; forming a layer of variable resistance material over saidsecond layer of conductive material, said variable resistance materialbeing able to change resistance under the influence of an appliedvoltage; and forming a third layer of conductive material over saidlayer of variable resistance material.
 23. The method of making a memorycell of claim 22, wherein said second layer of conductive material is ametal layer and said oxide binding layer comprises a metal from saidsecond layer diffused into said oxide layer.
 24. A method of making amemory system, comprising: forming an array of memory elements; andforming a memory cell associated with each memory element, whereinforming each memory cell includes: forming a first layer of conductivematerial; forming a dielectric layer on a surface of the first layer;forming an opening in the dielectric layer to expose a portion of asurface of said first layer; forming a conductive binding layer on thedielectric layer and on the exposed portion of the surface of the firstlayer, wherein the conductive binding is formed from an annealedinsulating material forming a second layer of conductive material on theconductive binding layer; forming a layer of doped chalcogenide materialon the second layer of conductive material; and forming a third layer ofconductive material on the layer of doped chalcogenide material.
 25. Themethod of making a memory system of claim 24, wherein said conductivebinding layer comprises an oxide layer and metal from said second layerdiffused into said oxide layer.
 26. A method of making an electronicsystem, comprising: forming a processor; and forming a memory systemcoupled to the processor, wherein forming the memory system includes:forming an array of memory elements; and forming a memory cellassociated with each memory element, wherein forming each memory cellincludes: forming a first layer of conductive material; forming an oxidebinding layer over a surface of said first layer, wherein said oxidebinding layer can be made conductive or at least semi-conductive;forming a second layer of conductive material on said oxide bindinglayer; forming a layer of variable resistance material over said secondlayer of conductive material, said variable resistance material beingable to change resistance under the influence of an applied voltage; andforming a third layer of conductive material on said layer of variableresistance material.
 27. The method of making an electronic system ofclaim 26, wherein said second layer of conductive material is a metallayer and said binding layer comprises a metal from said second layerdiffused into said oxide layer.